<!DOCTYPE html>



  


<html class="theme-next pisces use-motion" lang="zh-Hans">
<head><meta name="generator" content="Hexo 3.8.0">
  <meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<meta name="theme-color" content="#222">









<meta http-equiv="Cache-Control" content="no-transform">
<meta http-equiv="Cache-Control" content="no-siteapp">
















  
  
  <link href="/lib/fancybox/source/jquery.fancybox.css?v=2.1.5" rel="stylesheet" type="text/css">







<link href="/lib/font-awesome/css/font-awesome.min.css?v=4.6.2" rel="stylesheet" type="text/css">

<link href="/css/main.css?v=5.1.4" rel="stylesheet" type="text/css">


  <link rel="apple-touch-icon" sizes="180x180" href="/images/apple-touch-icon-next.png?v=5.1.4">


  <link rel="icon" type="image/png" sizes="32x32" href="/images/saiki.jpeg?v=5.1.4">


  <link rel="icon" type="image/png" sizes="16x16" href="/images/saiki.jpeg?v=5.1.4">


  <link rel="mask-icon" href="/images/logo.svg?v=5.1.4" color="#222">





  <meta name="keywords" content="Java,Effective Java,">










<meta name="description" content="Overrinding the equals method seems simple,but there are many ways to get it wrong,and consequences can be dire. The easiest way to avoid problem is not to override the equals method, in which case ea">
<meta name="keywords" content="Java,Effective Java">
<meta property="og:type" content="article">
<meta property="og:title" content="《Effective Java》 Item 10.Obey the general contract when overriding equals">
<meta property="og:url" content="http://yoursite.com/2019/05/28/Item 10.Obey the general contract when overriding equals/index.html">
<meta property="og:site_name" content="Penn">
<meta property="og:description" content="Overrinding the equals method seems simple,but there are many ways to get it wrong,and consequences can be dire. The easiest way to avoid problem is not to override the equals method, in which case ea">
<meta property="og:locale" content="zh-Hans">
<meta property="og:updated_time" content="2019-05-28T03:57:49.248Z">
<meta name="twitter:card" content="summary">
<meta name="twitter:title" content="《Effective Java》 Item 10.Obey the general contract when overriding equals">
<meta name="twitter:description" content="Overrinding the equals method seems simple,but there are many ways to get it wrong,and consequences can be dire. The easiest way to avoid problem is not to override the equals method, in which case ea">



<script type="text/javascript" id="hexo.configurations">
  var NexT = window.NexT || {};
  var CONFIG = {
    root: '/',
    scheme: 'Pisces',
    version: '5.1.4',
    sidebar: {"position":"left","display":"post","offset":12,"b2t":false,"scrollpercent":false,"onmobile":true},
    fancybox: true,
    tabs: true,
    motion: {"enable":true,"async":false,"transition":{"post_block":"fadeIn","post_header":"slideDownIn","post_body":"slideDownIn","coll_header":"slideLeftIn","sidebar":"slideUpIn"}},
    duoshuo: {
      userId: '0',
      author: '博主'
    },
    algolia: {
      applicationID: '',
      apiKey: '',
      indexName: '',
      hits: {"per_page":10},
      labels: {"input_placeholder":"Search for Posts","hits_empty":"We didn't find any results for the search: ${query}","hits_stats":"${hits} results found in ${time} ms"}
    }
  };
</script>



  <link rel="canonical" href="http://yoursite.com/2019/05/28/Item 10.Obey the general contract when overriding equals/">





  <title>《Effective Java》 Item 10.Obey the general contract when overriding equals | Penn</title>
  








</head>

<body itemscope="" itemtype="http://schema.org/WebPage" lang="zh-Hans">

  
  
    
  

  <div class="container sidebar-position-left page-post-detail">
    <div class="headband"></div>

    <header id="header" class="header" itemscope="" itemtype="http://schema.org/WPHeader">
      <div class="header-inner"><div class="site-brand-wrapper">
  <div class="site-meta ">
    

    <div class="custom-logo-site-title">
      <a href="/" class="brand" rel="start">
        <span class="logo-line-before"><i></i></span>
        <span class="site-title">Penn</span>
        <span class="logo-line-after"><i></i></span>
      </a>
    </div>
      
        <p class="site-subtitle">my blog</p>
      
  </div>

  <div class="site-nav-toggle">
    <button>
      <span class="btn-bar"></span>
      <span class="btn-bar"></span>
      <span class="btn-bar"></span>
    </button>
  </div>
</div>

<nav class="site-nav">
  

  
    <ul id="menu" class="menu">
      
        
        <li class="menu-item menu-item-home">
          <a href="/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-home"></i> <br>
            
            首页
          </a>
        </li>
      
        
        <li class="menu-item menu-item-about">
          <a href="/about/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-user"></i> <br>
            
            关于
          </a>
        </li>
      
        
        <li class="menu-item menu-item-tags">
          <a href="/tags/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-tags"></i> <br>
            
            标签
          </a>
        </li>
      
        
        <li class="menu-item menu-item-categories">
          <a href="/categories/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-th"></i> <br>
            
            分类
          </a>
        </li>
      
        
        <li class="menu-item menu-item-archives">
          <a href="/archives/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-archive"></i> <br>
            
            归档
          </a>
        </li>
      
        
        <li class="menu-item menu-item-schedule">
          <a href="/schedule/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-calendar"></i> <br>
            
            日程表
          </a>
        </li>
      
        
        <li class="menu-item menu-item-sitemap">
          <a href="/sitemap.xml" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-sitemap"></i> <br>
            
            站点地图
          </a>
        </li>
      
        
        <li class="menu-item menu-item-commonweal">
          <a href="/404/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-heartbeat"></i> <br>
            
            公益404
          </a>
        </li>
      

      
    </ul>
  

  
</nav>



 </div>
    </header>

    <main id="main" class="main">
      <div class="main-inner">
        <div class="content-wrap">
          <div id="content" class="content">
            

  <div id="posts" class="posts-expand">
    

  

  
  
  

  <article class="post post-type-normal" itemscope="" itemtype="http://schema.org/Article">
  
  
  
  <div class="post-block">
    <link itemprop="mainEntityOfPage" href="http://yoursite.com/2019/05/28/Item 10.Obey the general contract when overriding equals/">

    <span hidden itemprop="author" itemscope="" itemtype="http://schema.org/Person">
      <meta itemprop="name" content="Shen">
      <meta itemprop="description" content="">
      <meta itemprop="image" content="/images/saiki.jpeg">
    </span>

    <span hidden itemprop="publisher" itemscope="" itemtype="http://schema.org/Organization">
      <meta itemprop="name" content="Penn">
    </span>

    
      <header class="post-header">

        
        
          <h1 class="post-title" itemprop="name headline">《Effective Java》 Item 10.Obey the general contract when overriding equals</h1>
        

        <div class="post-meta">
          <span class="post-time">
            
              <span class="post-meta-item-icon">
                <i class="fa fa-calendar-o"></i>
              </span>
              
                <span class="post-meta-item-text">发表于</span>
              
              <time title="创建于" itemprop="dateCreated datePublished" datetime="2019-05-28T11:57:49+08:00">
                2019-05-28
              </time>
            

            

            
          </span>

          
            <span class="post-category">
            
              <span class="post-meta-divider">|</span>
            
              <span class="post-meta-item-icon">
                <i class="fa fa-folder-o"></i>
              </span>
              
                <span class="post-meta-item-text">分类于</span>
              
              
                <span itemprop="about" itemscope="" itemtype="http://schema.org/Thing">
                  <a href="/categories/技术/" itemprop="url" rel="index">
                    <span itemprop="name">技术</span>
                  </a>
                </span>

                
                
              
            </span>
          

          
            
          

          
          
             <span id="/2019/05/28/Item 10.Obey the general contract when overriding equals/" class="leancloud_visitors" data-flag-title="《Effective Java》 Item 10.Obey the general contract when overriding equals">
               <span class="post-meta-divider">|</span>
               <span class="post-meta-item-icon">
                 <i class="fa fa-eye"></i>
               </span>
               
                 <span class="post-meta-item-text">阅读次数&#58;</span>
               
                 <span class="leancloud-visitors-count"></span>
             </span>
          

          

          

          

        </div>
      </header>
    

    
    
    
    <div class="post-body" itemprop="articleBody">

      
      

      
        <p>Overrinding the equals method seems simple,but there are many ways to get it wrong,and consequences can be dire. The easiest way to avoid problem is not to override the equals method, in which case each instance of the class is equal only to itself.</p>
<p>when you override the equals method, you must adhere to its general contract. Here is contract, from the specification of Object:</p>
<p>-Reflexive<br>-Symmetric<br>-Transitive<br>-Consistent<br>-For any non-null refrence value x, <code>x.equals(null)</code> must return false. </p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br></pre></td><td class="code"><pre><span class="line">package com.zejian.test;</span><br><span class="line">import java.util.ArrayList;</span><br><span class="line">import java.util.List;</span><br><span class="line">/** * 反面例子 * @author zejian */</span><br><span class="line">public class AbnormalResult &#123;</span><br><span class="line">	public static void main(String[] args) &#123;</span><br><span class="line">		List&lt;A&gt; list = new ArrayList&lt;A&gt;();</span><br><span class="line">		A a = new A();</span><br><span class="line">		B b = new B();</span><br><span class="line">		list.add(a);</span><br><span class="line">		System.out.println(&quot;list.contains(a)-&gt;&quot; + list.contains(a));</span><br><span class="line">		System.out.println(&quot;list.contains(b)-&gt;&quot; + list.contains(b));</span><br><span class="line">		list.clear();</span><br><span class="line">		list.add(b);</span><br><span class="line">		System.out.println(&quot;list.contains(a)-&gt;&quot; + list.contains(a));</span><br><span class="line">		System.out.println(&quot;list.contains(b)-&gt;&quot; + list.contains(b));</span><br><span class="line">	&#125;</span><br><span class="line">	static class A &#123;</span><br><span class="line">		@Override</span><br><span class="line">		public boolean equals(Object obj) &#123;</span><br><span class="line">			return obj instanceof A;</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">	static class B extends A &#123;</span><br><span class="line">		@Override</span><br><span class="line">		public boolean equals(Object obj) &#123;</span><br><span class="line">			return obj instanceof B;</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>输出:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">list.contains(a)-&gt;true</span><br><span class="line"></span><br><span class="line">list.contains(b)-&gt;false</span><br><span class="line"></span><br><span class="line">list.contains(a)-&gt;true</span><br><span class="line"></span><br><span class="line">list.contains(b)-&gt;true</span><br></pre></td></tr></table></figure></p>
<p>list.contains()最终调用的是equals方法,代码list.contains(a)，实际上调用了a.equal(a[i]),其中a[i]是集合中的元素而且为B类型(只添加了b对象)，由于B类型肯定是A类型（B继承了A），所以a[i] instanceof A,结果为true</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br></pre></td><td class="code"><pre><span class="line">import java.util.HashMap;</span><br><span class="line">import java.util.Map;</span><br><span class="line">public class MapTest &#123;</span><br><span class="line">	public static void main(String[] args) &#123;</span><br><span class="line">		Map&lt;String,Value&gt; map1 = new HashMap&lt;String,Value&gt;();</span><br><span class="line">		String s1 = new String(&quot;key&quot;);</span><br><span class="line">		String s2 = new String(&quot;key&quot;);	</span><br><span class="line">		Value value = new Value(2);</span><br><span class="line">		map1.put(s1, value);</span><br><span class="line">		System.out.println(&quot;s1.equals(s2):&quot;+s1.equals(s2));</span><br><span class="line">		System.out.println(&quot;map1.get(s1):&quot;+map1.get(s1));</span><br><span class="line">		System.out.println(&quot;map1.get(s2):&quot;+map1.get(s2));</span><br><span class="line">		</span><br><span class="line">		</span><br><span class="line">		Map&lt;Key,Value&gt; map2 = new HashMap&lt;Key,Value&gt;();</span><br><span class="line">		Key k1 = new Key(&quot;A&quot;);</span><br><span class="line">		Key k2 = new Key(&quot;A&quot;);</span><br><span class="line">		map2.put(k1, value);</span><br><span class="line">		System.out.println(&quot;k1.equals(k2):&quot;+s1.equals(s2));</span><br><span class="line">		System.out.println(&quot;map2.get(k1):&quot;+map2.get(k1));</span><br><span class="line">		System.out.println(&quot;map2.get(k2):&quot;+map2.get(k2));</span><br><span class="line">	&#125;</span><br><span class="line">	</span><br><span class="line">	/**</span><br><span class="line">	 * 键</span><br><span class="line">	 * @author zejian</span><br><span class="line">	 *</span><br><span class="line">	 */</span><br><span class="line">	static class Key&#123;</span><br><span class="line">		private String k;</span><br><span class="line">		public Key(String key)&#123;</span><br><span class="line">			this.k=key;</span><br><span class="line">		&#125;</span><br><span class="line">		</span><br><span class="line">		@Override</span><br><span class="line">		public boolean equals(Object obj) &#123;</span><br><span class="line">			if(obj instanceof Key)&#123;</span><br><span class="line">				Key key=(Key)obj;</span><br><span class="line">				return k.equals(key.k);</span><br><span class="line">			&#125;</span><br><span class="line">			return false;</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">	</span><br><span class="line">	/**</span><br><span class="line">	 * 值</span><br><span class="line">	 * @author zejian</span><br><span class="line">	 *</span><br><span class="line">	 */</span><br><span class="line">	static class Value&#123;</span><br><span class="line">		private int v;</span><br><span class="line">		</span><br><span class="line">		public Value(int v)&#123;</span><br><span class="line">			this.v=v;</span><br><span class="line">		&#125;</span><br><span class="line">		</span><br><span class="line">		@Override</span><br><span class="line">		public String toString() &#123;</span><br><span class="line">			return &quot;类Value的值－－&gt;&quot;+v;</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>结果:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"></span><br><span class="line">s1.equals(s2):true</span><br><span class="line">map1.get(s1):类Value的值－－&gt;2</span><br><span class="line">map1.get(s2):类Value的值－－&gt;2</span><br><span class="line">k1.equals(k2):true</span><br><span class="line">map2.get(k1):类Value的值－－&gt;2</span><br><span class="line">map2.get(k2):null</span><br></pre></td></tr></table></figure></p>
<p>在重写equals() 方法时，一般都是推荐使用getClass来进行类型判断（除非所有的子类有统一的语义才使用instanceof),防止出现对于不同的子类e1,e2, 父类p即等于e1又等于e2.</p>
<p>参考:<a href="https://blog.csdn.net/javazejian/article/details/51348320#" target="_blank" rel="noopener">https://blog.csdn.net/javazejian/article/details/51348320#</a></p>

      
    </div>
    
    
    

    

    
      <div>
        <div style="padding: 10px 0; margin: 20px auto; width: 90%; text-align: center;">
  <div>这两个图片是什么?可以扫吗?</div>
  <button id="rewardButton" disable="enable" onclick="var qr = document.getElementById('QR'); if (qr.style.display === 'none') {qr.style.display='block';} else {qr.style.display='none'}">
    <span>打赏</span>
  </button>
  <div id="QR" style="display: none;">

    
      <div id="wechat" style="display: inline-block">
        <img id="wechat_qr" src="/images/wechatPay.png" alt="Shen 微信支付">
        <p>微信支付</p>
      </div>
    

    
      <div id="alipay" style="display: inline-block">
        <img id="alipay_qr" src="/images/aliPay.png" alt="Shen 支付宝">
        <p>支付宝</p>
      </div>
    

    

  </div>
</div>

      </div>
    

    

    <footer class="post-footer">
      
        <div class="post-tags">
          
            <a href="/tags/Java/" rel="tag"># Java</a>
          
            <a href="/tags/Effective-Java/" rel="tag"># Effective Java</a>
          
        </div>
      

      
      
      

      
        <div class="post-nav">
          <div class="post-nav-next post-nav-item">
            
              <a href="/2019/05/28/CountDowbLatch 和 CyclicBarrier/" rel="next" title="CountDownLatch adn CyclicBarrier">
                <i class="fa fa-chevron-left"></i> CountDownLatch adn CyclicBarrier
              </a>
            
          </div>

          <span class="post-nav-divider"></span>

          <div class="post-nav-prev post-nav-item">
            
              <a href="/2019/05/28/Item1. Consider static factory methods instead of constructors/" rel="prev" title="《Effective Java》Item1. Consider static factory methods instead of constructors">
                《Effective Java》Item1. Consider static factory methods instead of constructors <i class="fa fa-chevron-right"></i>
              </a>
            
          </div>
        </div>
      

      
      
    </footer>
  </div>
  
  
  
  </article>



    <div class="post-spread">
      
    </div>
  </div>


          </div>
          


          

  
    <div class="comments" id="comments">
      <div id="lv-container" data-id="city" data-uid="MTAyMC80MjA1OS8xODYwNg=="></div>
    </div>

  



        </div>
        
          
  
  <div class="sidebar-toggle">
    <div class="sidebar-toggle-line-wrap">
      <span class="sidebar-toggle-line sidebar-toggle-line-first"></span>
      <span class="sidebar-toggle-line sidebar-toggle-line-middle"></span>
      <span class="sidebar-toggle-line sidebar-toggle-line-last"></span>
    </div>
  </div>

  <aside id="sidebar" class="sidebar">
    
      <div id="sidebar-dimmer"></div>
    
    <div class="sidebar-inner">

      

      

      <section class="site-overview-wrap sidebar-panel sidebar-panel-active">
        <div class="site-overview">
          <div class="site-author motion-element" itemprop="author" itemscope="" itemtype="http://schema.org/Person">
            
              <img class="site-author-image" itemprop="image" src="/images/saiki.jpeg" alt="Shen">
            
              <p class="site-author-name" itemprop="name">Shen</p>
              <p class="site-description motion-element" itemprop="description">Penn's blog</p>
          </div>

          <nav class="site-state motion-element">

            
              <div class="site-state-item site-state-posts">
              
                <a href="/archives/">
              
                  <span class="site-state-item-count">117</span>
                  <span class="site-state-item-name">日志</span>
                </a>
              </div>
            

            
              
              
              <div class="site-state-item site-state-categories">
                <a href="/categories/index.html">
                  <span class="site-state-item-count">1</span>
                  <span class="site-state-item-name">分类</span>
                </a>
              </div>
            

            
              
              
              <div class="site-state-item site-state-tags">
                <a href="/tags/index.html">
                  <span class="site-state-item-count">26</span>
                  <span class="site-state-item-name">标签</span>
                </a>
              </div>
            

          </nav>

          

          

          
          

          
          

          

        </div>
      </section>

      

      

    </div>
  </aside>


        
      </div>
    </main>

    <footer id="footer" class="footer">
      <div class="footer-inner">
        <div class="copyright">&copy; <span itemprop="copyrightYear">2020</span>
  <span class="with-love">
    <i class="fa fa-user"></i>
  </span>
  <span class="author" itemprop="copyrightHolder">Shen</span>

  
</div>


  <div class="powered-by">由 <a class="theme-link" target="_blank" href="https://hexo.io">Hexo</a> 强力驱动</div>



  <span class="post-meta-divider">|</span>



  <div class="theme-info">主题 &mdash; <a class="theme-link" target="_blank" href="https://github.com/iissnan/hexo-theme-next">NexT.Pisces</a> v5.1.4</div>




        







        
      </div>
    </footer>

    
      <div class="back-to-top">
        <i class="fa fa-arrow-up"></i>
        
      </div>
    

    

  </div>

  

<script type="text/javascript">
  if (Object.prototype.toString.call(window.Promise) !== '[object Function]') {
    window.Promise = null;
  }
</script>









  












  
  
    <script type="text/javascript" src="/lib/jquery/index.js?v=2.1.3"></script>
  

  
  
    <script type="text/javascript" src="/lib/fastclick/lib/fastclick.min.js?v=1.0.6"></script>
  

  
  
    <script type="text/javascript" src="/lib/jquery_lazyload/jquery.lazyload.js?v=1.9.7"></script>
  

  
  
    <script type="text/javascript" src="/lib/velocity/velocity.min.js?v=1.2.1"></script>
  

  
  
    <script type="text/javascript" src="/lib/velocity/velocity.ui.min.js?v=1.2.1"></script>
  

  
  
    <script type="text/javascript" src="/lib/fancybox/source/jquery.fancybox.pack.js?v=2.1.5"></script>
  


  


  <script type="text/javascript" src="/js/src/utils.js?v=5.1.4"></script>

  <script type="text/javascript" src="/js/src/motion.js?v=5.1.4"></script>



  
  


  <script type="text/javascript" src="/js/src/affix.js?v=5.1.4"></script>

  <script type="text/javascript" src="/js/src/schemes/pisces.js?v=5.1.4"></script>



  
  <script type="text/javascript" src="/js/src/scrollspy.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/post-details.js?v=5.1.4"></script>



  


  <script type="text/javascript" src="/js/src/bootstrap.js?v=5.1.4"></script>



  


  




	





  





  
    <script type="text/javascript">
      (function(d, s) {
        var j, e = d.getElementsByTagName(s)[0];
        if (typeof LivereTower === 'function') { return; }
        j = d.createElement(s);
        j.src = 'https://cdn-city.livere.com/js/embed.dist.js';
        j.async = true;
        e.parentNode.insertBefore(j, e);
      })(document, 'script');
    </script>
  












  





  

  
  <script src="https://cdn1.lncld.net/static/js/av-core-mini-0.6.4.js"></script>
  <script>AV.initialize("Gst71Gv0w5HKejm5H7LuG0XI-gzGzoHsz", "aoFAyHFDKihGTWWhHX0p8byC");</script>
  <script>
    function showTime(Counter) {
      var query = new AV.Query(Counter);
      var entries = [];
      var $visitors = $(".leancloud_visitors");

      $visitors.each(function () {
        entries.push( $(this).attr("id").trim() );
      });

      query.containedIn('url', entries);
      query.find()
        .done(function (results) {
          var COUNT_CONTAINER_REF = '.leancloud-visitors-count';

          if (results.length === 0) {
            $visitors.find(COUNT_CONTAINER_REF).text(0);
            return;
          }

          for (var i = 0; i < results.length; i++) {
            var item = results[i];
            var url = item.get('url');
            var time = item.get('time');
            var element = document.getElementById(url);

            $(element).find(COUNT_CONTAINER_REF).text(time);
          }
          for(var i = 0; i < entries.length; i++) {
            var url = entries[i];
            var element = document.getElementById(url);
            var countSpan = $(element).find(COUNT_CONTAINER_REF);
            if( countSpan.text() == '') {
              countSpan.text(0);
            }
          }
        })
        .fail(function (object, error) {
          console.log("Error: " + error.code + " " + error.message);
        });
    }

    function addCount(Counter) {
      var $visitors = $(".leancloud_visitors");
      var url = $visitors.attr('id').trim();
      var title = $visitors.attr('data-flag-title').trim();
      var query = new AV.Query(Counter);

      query.equalTo("url", url);
      query.find({
        success: function(results) {
          if (results.length > 0) {
            var counter = results[0];
            counter.fetchWhenSave(true);
            counter.increment("time");
            counter.save(null, {
              success: function(counter) {
                var $element = $(document.getElementById(url));
                $element.find('.leancloud-visitors-count').text(counter.get('time'));
              },
              error: function(counter, error) {
                console.log('Failed to save Visitor num, with error message: ' + error.message);
              }
            });
          } else {
            var newcounter = new Counter();
            /* Set ACL */
            var acl = new AV.ACL();
            acl.setPublicReadAccess(true);
            acl.setPublicWriteAccess(true);
            newcounter.setACL(acl);
            /* End Set ACL */
            newcounter.set("title", title);
            newcounter.set("url", url);
            newcounter.set("time", 1);
            newcounter.save(null, {
              success: function(newcounter) {
                var $element = $(document.getElementById(url));
                $element.find('.leancloud-visitors-count').text(newcounter.get('time'));
              },
              error: function(newcounter, error) {
                console.log('Failed to create');
              }
            });
          }
        },
        error: function(error) {
          console.log('Error:' + error.code + " " + error.message);
        }
      });
    }

    $(function() {
      var Counter = AV.Object.extend("Counter");
      if ($('.leancloud_visitors').length == 1) {
        addCount(Counter);
      } else if ($('.post-title-link').length > 1) {
        showTime(Counter);
      }
    });
  </script>



  

  

  
  

  

  

  

</body>
</html>
